How to implement a flutter layout more easily？

Question

I have a layout effect, I don't know how to implement it more easily? I have six or N child widgets, placed in a parent widget with two child widgets per row, each widget is 50% the width of the parent widget and height is the height /rows of the parent widget.

I can use column, row expanded to do this, but I don't think it's simple enough.If my child widgets are intermediate, I don't know how to create them dynamically.

The layout effect what I want to achieve:

The way I want to do it is the following pseudocode I can do it in Android and iOS, but I don't know how to do it with flutter.

var parentWidget = Widget()

for (var i = 0; i < 6; i++) {
    var child = Widget()
    parentWidget.add(child)
}

The Flutter is implemented as follows. I can use column,row expanded to do this, but I don't think it's simple enough. If my child widgets are indeterminate, I don't know how to create them dynamically.

Expanded(
      child: Column(
        children: <Widget>[
          Expanded(
            flex: 1,
            child: Row(children: <Widget>[
              Expanded(child: Text("1"),),
              Expanded(child: Text("1"),),
            ],)
          ),
          Expanded(
            flex: 1,
            child:Row(children: <Widget>[
              Expanded(child: Text("1"),),
              Expanded(child: Text("1"),),
            ],),
          ),
          Expanded(
            flex: 1,
            child: Row(children: <Widget>[
              Expanded(child: Text("1"),),
              Expanded(child: Text("1"),),
            ],),
          )
        ],
      ),
    )

@PhucTran yes，But I don't want the scrolling effect, I just want the child widgets to split the parent widget to fit different screen sizes, so there aren't too many children, maybe six, maybe eight — user7887727
– user7887727, Commented Jan 15, 2019 at 2:51
It's only scrollable if the number of items is big enough (some are out of screens) — Phuc Tran
– Phuc Tran, Commented Jan 15, 2019 at 2:53
Why not use a GridView? docs.flutter.io/flutter/widgets/GridView-class.html — ishaan
– ishaan, Commented Jan 15, 2019 at 5:52

user7887727 · Accepted Answer · 2019-01-15 08:13:11Z

I've come up with a way to deal with this requirement by calculating the width and height of each child widget and then placing them in wrap to arrange themselves


class RowFixedWrap extends StatefulWidget {
  final double spacing;
  final double runSpacing;
  final int columnCount;
  final List<Widget> childern;

  RowFixedWrap(
      {Key key, this.spacing, this.runSpacing, this.columnCount, this.childern})
      : super(key: key);

  @override
  State<StatefulWidget> createState() {
    return _FixedWrapState();
  }
}

class _FixedWrapState extends State<RowFixedWrap> {
  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        var itemWidth =
            (constraints.maxWidth - widget.spacing * (widget.columnCount - 1)) /
                widget.columnCount;
        var rows = widget.childern.length % widget.columnCount != 0
            ? (widget.childern.length ~/ widget.columnCount) + 1
            : (widget.childern.length ~/ widget.columnCount);
        var itemHeight =
            (constraints.maxHeight - widget.runSpacing * (rows - 1)) / rows;

        return Wrap(
            spacing: widget.spacing,
            runSpacing: widget.runSpacing,
            children: widget.childern.map((widget) {
              return SizedBox(
                width: itemWidth,
                height: itemHeight,
                child: widget,
              );
            }).toList());
      },
    );
  }
}

Expanded(
        child: Padding(
      padding: const EdgeInsets.all(10.0),
      child: RowFixedWrap(
        spacing: 10,
        runSpacing: 10,
        columnCount: 2,
        childern: <Widget>[
          Container(
            color: Colors.red,
          ),
          Container(
            color: Colors.red,
          ),
          Container(
            color: Colors.red,
          ),
          Container(
            color: Colors.red,
          ),
        ],
      ),
    ));

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